<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="lib/vue.js"></script>
    <style>
        .one{
            color: red;
        }
        .two{
            background-color: blueviolet;
        }
    </style>
</head>
<body>
    <div id="root">
        <p class="one">1</p>
        <p :class="co">1</p>
        <p :class="co">1</p>
        <p :class="[co,bg]">1</p>
        <p :class="{co:false,bg:true}">1</p>
    </div>
</body>
<script>
    new Vue({
        el : '#root',
        data : {
            co : 'one',
            bg : 'two',
            arr : ['one','two']
        }
    })
</script>
</html>